1. Field of the Invention
The present invention relates to a system for tagging lumber. In particular, the present invention relates to a system that includes an automated apparatus and method for affixing labels (xe2x80x9ctagsxe2x80x9d) that carry identifying indicia onto the ends of individual boards in a pack of lumber.
2. Discussion of Background
Lumber is usually labeled (xe2x80x9ctaggedxe2x80x9d) to identify the manufacturer, the species of wood or the type of product, the grade, and various other data useful to consumers (wholesalers and retailers, homeowners, handymen, carpenters, builders, etc.). Identifying labels are sometimes applied by the manufacturer, for example, by stamping individual boards with an inked design, by embossing, or by attaching a paper or plastic tag to the boards. However, most lumber is not sold directly to the end user. Rather, it is bundled and shipped from a primary manufacturer (such as a sawmill) to a secondary manufacturer (a kiln or surfacing yard), then to a wholesaler, and finally to a retailer. At each stage in this process, the lumber may be unpacked, graded (or regraded), sorted (by size, grade, and composition), and repacked. The bundled units (xe2x80x9cpacksxe2x80x9d or xe2x80x9cstacksxe2x80x9d) that are ultimately shipped to a retail outlet may each contain boards of the same or different length, width, grade, and composition. Each pack in a shipment may differ from the others; each layer (xe2x80x9ccoursexe2x80x9d) of a pack may differ from the other layers. Even in shipments of woods such as Southern Yellow Pine (xe2x80x9cSYPxe2x80x9d) where the packs tend to be quite similar, the dimensions of boards in different layers of a pack may vary.
With the growing popularity of bar code scanners at retail checkout counters, many wholesalers and retail distribution centers label each board individually with a label that can be read by these types of scanners. Labels can be applied by hand, for example, with devices such as those disclosed by Vanderwiel (U.S. Pat. No. 5,292,048), Reitmeier, et al. (U.S. Pat. No. 5,014,896), and Hurd (U.S. Pat. No. 3,476,302). Vanderwiel""s semiautomatic lumber tag stapler includes a conventional pneumatic staple gun, a holder for a roll of tags, a rotatable pivot indexing arm that moves a tag into position for stapling, a cylinder for rotating the indexing arm, and an index stop pin for limiting pivoting of the arm.
Reitmeier, et al. disclose a trigger-operated pneumatic staple gun which both staples and cuts labels. This device includes a guide which directs the labels through a cutter and underneath the staple gun head, and a pair of pneumatic cylinders with a common spool valve. One of the cylinders is connected to a label advance head which brings labels into position; the other is connected to a cutter which cuts the just-stapled label from the remainder of the roll.
Hurd""s portable stapler is used for attaching wallboard to a supporting framework. The device includes an attachment with a reel of wire, a slidable shoe, and a staple guide that, when mounted to a conventional stapler, acts as a mechanism for regulating the driving force and thereby minimizing damage to the wallboard.
No matter what hand tool is selected, hand-labeling lumber is slow, labor-intensive, and expensive, and has a high potential for error due to the variability of the boards in atypical wholesaler""s or retailer""s pack. Individual boards are difficult to distinguish from other boards of similar species, grade, thickness, width, and length.
Automated and semi-automated apparatus for tagging lumber is also available. In U.S. Pat. No. 5,775,497, Lippincott discloses a lumber stamper for embossing the ends of a plurality of stacked pieces. The apparatus includes an embossing plate, a press plate with a plurality of movable segments, a lumber support for holding stacked, parallel lumber pieces between the plates, a drive mechanism for moving the press plate segments between their retracted and extended positions so as to emboss the ends of a clamped stack of lumber, and a controller. The embossing and press plates are mounted on movable carriers, allowing the operator to adjust the distance between these plates to accommodate lumber of different lengths.
Aman, et al. (U.S. Pat. No. 5,307,294) use a focused beam or a movable scanner which collects topological information about a stack of lumber, with a processor which translates this information into the xe2x80x9ctally countxe2x80x9d or xe2x80x9cend tally,xe2x80x9d defined as the number of pieces of lumber with each particular combination of width, thickness, and length. This information can be used to determine the exact location of individual boards within as tack, generating unique labels for each board, and applying the labels (U.S. Pat. No. 5,674,335).
Walker, Jr.""s automated tagging apparatus (U.S. Pat. No. 5,208,962) is used for stapling tags to the ends of individual boards passing along a conveyor belt. The apparatus includes a conveyer operating at approximately one foot/second, a labeling system with a roll of tags and a conventional stapler, a sensor that activates the labeling system when a board passes over the sensor, and a roller that lifts the boards to release the sensor. Before reaching the sensor, the boards are fed through a chute that aligns the ends.
Prim, et al. (U.S. Pat. No. 4,392,204) provide a computer-controlled umber marking system that includes a trimming system with a chain/lug conveyer, a pulse generator that produces a pulse for each increment of conveyor movement, a console where an operator views the boards and inputs grade data, a xe2x80x9ccurtainxe2x80x9d of optical detectors which determine the maximum available length of each board, and a second set of optical detectors that determine the width of each board based on the number of pulses during the period that a light beam is broken by each board. This grade, length, and width data is collated and output to an embossing mechanism that marks the ends of the boards on a piece-by-piece basis.
Moore""s wood handling machine (U.S. Pat. No. 4,324,519) includes a rectangular support bed that holds a stack of precut boards in layers, a wheeled carriage that holds a vertical support frame and a hydraulic piston-and-cylinder assembly, a pneumatic clamping device to clamp the stack and hold it in alignment, a pushing device for pushing one layer at a time of the stacked boards in order to expose the surface of the next layer for marking, and a stop bar to prevent movement of the next adjacent layer of boards during operation of the pushing device. The operation of the apparatus is described in the paragraph starting on line 51, Col. 5 (note that the apparatus is manually controlled).
While automated or semi-automated tagging apparatus is faster than hand-labeling, some presently available apparatus requires that the individual boards be placed onto a conveyer and moved past a stapler, embosser, or other marking device. Other such apparatus requires a determination of the number of boards in a pack (and the dimensions of the individual boards) before the tags can be applied. There remains a need for a simple, rugged, cost-effective system for tagging the ends of boards in a pack.
According to its major aspects and broadly stated, the present invention is an automated apparatus and method for labeling (xe2x80x9ctaggingxe2x80x9d) individual boards in a pack of lumber. The apparatus includes a support frame, a jump chain conveyor, a lift, a back stop or bump plate, a detector for determining the position of a leading board within the pack, a labeling assembly, a positioning assembly for moving the labeling assembly in three dimensions, and a computer system with a PLC (i.e., programmable logic controller) and an HMI (i.e., a human-machine interface such as a keyboard, keypad, touchpad or touch screen, voice input, or other suitable interface).
In operation, a pack of lumber is placed onto the jump chains, lifted, and conveyed by the moving chains until it abuts the back stop, where it is lowered onto the support frame. The operator inputs identifying information about the pack into the computer, for example, the dimensions of the boards, the size of the pack (typically a full, xc2xd, or xc2xc pack, although other sizes may also be useful), the grade, composition, and, optionally, customer information such as the customer""s name, brand name or logo. The computer system uses this information to compute the number of labels needed, the approximate distance between the centers of the boards in each course, and the approximate distance between the centers of neighboring boards in adjacent courses.
Under computer control, the detector automatically locates the position of the first, leading board in the pack; then, starting with the leading board, the positioning assembly automatically moves the labeling assembly to each board in turn to print and affix a label. (For stand-alone operation, packs of lumber are simply loaded onto the support frame by a forklift or other suitable lifting apparatus, tagged, and removed.) The labels may be placed approximately at the centers of the boards, or at some other convenient location. The apparatus is capable of attaching identifying labels (xe2x80x9ctagsxe2x80x9d) to the individual boards in a pack with minimal intervention by a human operator, with increased accuracy and increased speed over manual tagging.
An important feature of the present invention is the positioning assembly, which is movable in three dimensions via servo or stepper motors, pneumatic (air or other gas) or hydraulic cylinders, or other suitable devices. For example, the positioning assembly may include three servo motors for moving the labeling assembly in three orthogonal directions (X, Y, and Z) for precise, three-dimensional positioning and accurate tagging. Alternatively, two servo motors move the labeling assembly in two orthogonal directions (such as the X and Y directions), while an air cylinder moves it in the Z direction. The positioning assembly also operates in conjunction with the detector to precisely locate the position of the leading board, and to deter accidental xe2x80x9cslammingxe2x80x9d of the labeling assembly into the pack.
Another important feature of the present invention is the computer system which controls the operation of the apparatus. The computer system can be user-programmable; alternatively, dedicated systems may also be useful. Solely by inputting the dimensions of the boards in the pack into the computer system, the operator is able to program the computer system to remotely control the apparatus to affix labels to each board in turn, starting with a selected leading board (typically, the leading board is located at one of the four corners of the pack). If desired, the operator can input additional information about the pack to be printed on the labels, including but not necessarily limited to the species of wood (pine, birch, oak, etc.), the type of wood product (natural wood, fiberboard, chipboard, compositions such as Masonite(trademark), etc.), the grade, the customer""s name, the customer""s logo, price, bar code, etc. Labels can be pre-printed with some or all of the desired information; alternatively, the information can be printed xe2x80x9con the flyxe2x80x9d during labeling operations. Programming the computer to print all identifying information in real time, during the labeling process, eliminates the need to change out rolls of tags after processing each pack or order.
Another feature of the present invention is the detector, which is preferably mounted to the Z-axis carriage of the positioning assembly (other locations may also be useful). The detector includes an optical, radiofrequency (xe2x80x9cRFxe2x80x9d), or ultrasonic sensor for determining the position of a leading board within the pack. Once the position of the leading board is known, the computer automatically operates the positioning assembly to move the labeling assembly to the leading board, then to each of the remaining boards in turn.
Still another feature of the present invention is the computer-controlled labeling assembly, which is mounted to the positioning assembly for three-dimensional movement. The labeling assembly includes a printer for generating labels, and a stapler, glue gun, or other suitable device for affixing the labels to the boards.
Yet another feature of the present invention is the support frame with the conveyor and back stop. The conveyor is preferably a jump chain conveyor or chain-lug conveyor of the type familiar to those skilled in the art, with at least two parallel, endless chains moving in a path defined by an elongated loop with upper and lower runs. In this type of conveyor, each chain wraps around a drive sprocket. The drive sprockets are mounted on a common drive shaft, which is rotated by a motor operably connected to the shaft. The chains lift and move a pack of lumber until it abuts the back stop, where the pack is lowered onto the support frame to be tagged. The back stop ensures that the ends which are to be tagged are approximately aligned in a vertical plane.
Still another feature of the present invention is the mode of operation of the apparatus, which can operate in-line or in stand-alone mode as described above. Given the identifying information provided by the operator, the detector automatically determines the position of the leading board; the computer system controls movement of the positioning assembly and tags of every board in the pack without the need for other human intervention. This makes for rapid, cost-effective labeling, since there is no need to precisely specify the positions of the individual boards in the pack before starting labeling operations.